Tension stand



United States Patent 3,390,824 TENSION STAND Alexander V. Alexelf,Cleveland, Ohio, assignor to Industrial Ovens, Incorporated, Cleveland,Ohio, a corporation of Ohio Continuation of application Ser. No.341,550, Jan. 31, 1964. This application Dec. 21, 1966, Ser. No. 603,6864 Claims. (Cl. 226-195) ABSTRACT OF THE DISCLOSURE A tension standhaving an array of cylindrical rolls which are spaced from each otherand positioned for wrapping contact in a given sequence by a passing weband which are linked to each other by angular motion transmitting meansfor establishing substantially fixed ratios between the angulardisplacements of the linked rolls. At least one of the rolls is spacedfrom the remainder of the rolls to establish at least one long reach ofweb which reach substantially exceeds in length the average diameter ofthe rolls in the array.

This is a continuation of application Ser. No. 341,550 filed Jan. 31,1964, now abandoned.

The present invention relates to tension stands for strips. For purposesof this application, strips are to be understood to include Webs such asmetal sheet, paper, textiles, films, and wide tape, and to also includewires, rods, narrow tapes, tubings, and filaments, such as nylon, rayonand glass fiber.

In the processing of strip material, it is usually necessary to overcomeand/ or resist the imposition of tension on the strip material duringthe treatment of the strip so that the imposition of such tension isconfined to desired treating zones. For example, in the treatment ofnylon fabric, it is desirable to subject the fabric to a hot-stretchtreatment in which the fabric is heated and stretched following acoating or impregnating step. During the hotstretch treatment, tensionis imposed on the strip and this tension may be in the order of 20 tonsor more; and during the coating or impregnating step, the tension isconsiderably less than 20 tons.

To accommodate the differences in tension along the entire strip, it isnecessary to provide .roll arrays or tension stands to overcome and/ orresist such impositions of tension. The tension stands are located inthe processing line at positions where it is desired to maintain tensiondifferentials in the strip. Conventional tension stands for this purposeemploy driven, geared r-o'lls that are arranged so that the strip willhave a high total angle of wrap (say 2000 degrees) through the tensionstands. The rolls are conventionally nested and arranged in a compactarray with short web reaches between successive rolls.

If such a conventional tension stand is employed as a hold back stand,i.e., the tension of the outgoing strip is considerably greater thanthat of the incoming strip, the outgoing strip will slip on the last twoor three rolls when operating at line speeds. This slippage is notsmooth and continuous over these rolls, but is a pulsating slippage.These pulses are violent and if the strip is under a tension of 12,500pounds at the outgoing end of the tension stand and if the strip istraveling at 100 yards per minute, the frequency of the pulses may bebetween 8 and 10 pulses per second, and the pulses may reduce thestrength of the processed material by approximately 10 percent.

If the tension stand is employed as an intermediate type pull rollstand, as for example where the outgoing strip is maintained under arelatively high tension and the incoming strip is maintained under aneven higher tension, the rolls at the incoming end of the tension standwill 3,390,824 Patented July 2, 1968 act as a pull stand while the rollsat the outgoing end of the stand will act as a hold back stand. Thisproduces pulses in the strip which are similar to the violent pulsesproduced by the previously described stretching action, except that theyoccur at an intermediate location in the roll stand. In either case,however, the rolls of the tension stand and their gears are subjected tosevere moment imbalances and resulting rocking loads and gear chatter orreverse pounding on the gear teeth. A solution to this problem does notreside in merely providing heavy and costly structure to resist theseloads, since this undesirably tends to cause absorption of the loads bythe material itself and may tend to further contribute to the weakeningof the material.

It is an object of this invention to provide a roll array for a tensionstand that overcomes many of these prior art problems.

It is a more particular object of this invention to provide a tensionstand having a roll array that will minimize violent pulsations throughthe tension stand by permitting stretch and/ or shrinkage to be moreevenly distributed.

The invention contemplates disposing at least one of the intermediaterolls in a tension stand from its conventional, closely spacedrelationship with other rolls so that at least one reach of the websubstantially exceeds in length the average diameter of the rolls in thetension stand.

The features and advantages of the invention will be more apparent fromthe following description of a specific example thereof.

In the drawing:

FIGURE 1 is a diagrammatic illustration of a conventional tension stand;

FIGURE 2 is a diagrammatic illustration of a tension stand embodying theinvention; and

FIGURE 3 is a diagrammatic illustration of another embodiment of theinvention.

A conventional tension stand is illustrated in FIGURE 1, and the tensionstand includes an array of rolls 10. A web W is entrained around therolls 10 to provide a maximum angle of wrap between each roll 10 and theweb. Each roll 10 is provided with angular motion transmitting meanssuch as gears 11. The gears 11 mesh with each other according to thesequence established by the web W. One of the rolls 10 is connected to ahold back means, such as the drive shaft of a high torque capacity DC.motor (not shown). The tension capacity of the stand is correlated tothe total degrees of wrap between the web W and the rolls 10.

The conventional roll arrangement illustrated in FIG- URE 1 results inrelatively short reaches R between adjacent rolls 10. If the tensionstand is employed as a hold back stand, with, for example, a web tensionof 25,000 pounds at the outfeed end of the tension stand and a webtension of 2,000 pounds at the infeed end of the stand, then at normalline speeds slippage takes place in the form of short, violent pulses atthe last few rolls of the stand.

If the tension stand illustrated in FIGURE 1 is employed as anintermediate type pull roll stand, with, for example, an infeed webtension of 25,000 pounds and an outfeed web tension of 5,000 pounds,rolls adjacent the infeed end of the tension stand will act as a pullroll stand, While the rolls adjacent the outfeed end of the tensionstand will act as a hold back stand. In such an arrangement, thepreviously described pulsating action will occur at an intermediatelocation within the stand.

FIGURE 2 illustrates a tension stand embodying the invention. Thetension stand includes an array of rolls 12. A web W is entrainedthrough the rolls 12 in a predetermined sequence to establish a maximumangle of wrap betwen each roll 12 and the web. Each roll 12 is providedwith angular motion transmitting means such as gears 13. The gears 13and a gear 14 establish a gear train that drives the rolls in thesequence established by the web W. One of the rolls 12 is connected to ahold back means, such as the drive shaft of a high torque capacity DC.motor (not shown). The tension capacity of the stand is correlated tothe total degrees of wrap between the web W and the rolls 12.

A roll 15, which would conventionally be associated with the gear 14, isspaced from its immediately adjacent upstream and downstream rolls toprovide relatively lOng reaches L, as compared to the relatively shortreaches R that are established between the rolls 12. The relatively longreaches L provide an additional unwrapped length of strip material inthe tension stand. At even the highest line speeds, the provision ofthis additional unwrapped length greatly minimizes the previouslydescribed pulsing in the web. The roll 15 may be driven by a linkagefrom the gear 14 if it is necesary to utilize the wrapped surface of theroll 15 as an additional tensioning means. If the degree of web wrapover the rolls 12 is adequate for the imposition of a predeterminedtension on the Web W, the roll 15 may be an idler roll.

The particular roll that establishes the relatively long reaches L isimmaterial as long as these reaches are established at an intermediatestage in the tension stand. For purposes of this application, anintermediate stage is to be understood as a zone between the point orline of contact that the web makes with the first roll at the infeed endof the tension stand and the line or point of contact that the web makeswith the roll at the outfeed end of the tension stand.

It should also be appreciated that minimization or elimination ofpulsation may be enhanced by increasing the lengths and the number ofthe relatively long reaches L that are established in the tension stand.Thus, it may be desirable in some instances to position more than oneroll a substantial distance from its immediately adjacent upstream anddownstream rolls. In any case, however, a reach L should be greater thanthe average diameter of the rolls in the tension stand in order toeifectively minimize pulsations in the web.

In FIGURE 3, a tension stand is illustrated that includes an array ofrolls 16 that are all positioned remote from their adjacent upstream anddownstream rolls to provide relatively long reaches L of a web W whichis trained through the rolls. The rolls 16 are driven in the directionestablished by the web W by suitable angular motion transmitting means,such as the gears 17, which are associated with the rolls 16. Thisdriving relationship between the rolls 16 is further established byintermediate gears 18. One of the rolls 16 or one of the intermediategears 18 are connected to a hold back means, such as the drive shaft ofa high torque capacity DC motor (not shown). The tension capacity of thestand is correlated to the total degrees of wrap between the web W andthe rolls 16.

The invention is not restricted to the slavish imitation of each andevery one of the details described above, which have been set forthmerely by way of example with the intent of most clearly setting forththe teachings of the invention. Obviously, devices may be provided whichchange, eliminate, or add certain specific details without departingfrom the invention.

What is claimed is:

1. A web tension stand for maintaining a substantial tensiondifferential between the portions of web entering the stand and theportions of web leaving the stand comprising an array of rolls includinga plurality of webtension-absorbing rolls positioned so that a web maybe sequentially wrapped therearound with contact between such web andsaid web-tension-absorbing rolls along a substantial peripheral portionthereof, rigid torque transmitting means interconnecting said rollsincluding rigid elements operable in both tension and compression tomaintain a constant fixed ratio between the angular displacements ofsaid rolls with substantially no lost motion or free travel even whentorque impulses occur, said rolls being operable to maintain a firsttension in web at one end of said array and a second tensionsubstantially different than said first tension in such web at the otherend of said array, the tension in such web in the reaches between saidweb-tension-absorbing rolls progressively changing from said firsttension to said second tension, and said array including at least oneroll establishing at an intermediate stage in the sequence of such webthrough said array at least one long reach of web which substantiallyexceeds the length of the average diameter of said web-tension-absorbingrolls whereby pulsating slippage between such web and said rolls issubstantially reduced.

2. A web tension stand as set forth in claim 1 wherein said rigid torquemeans includes meshing gears interconnecting said web-tension-absorbingrolls with at least one gear mounted on each roll.

3. A web tension stand as set forth in claim 2 wherein the gears mountedon each roll directly mesh with at least one gear on another roll.

4. A web tension stand as set forth in claim 2 wherein idler gear meansinterconnect at least two of said ears mounted on said rolls.

References Cited UNITED STATES PATENTS 2,059,979 11/1936 Aiken 226--l192,793,033 5/1957 scelen 226-l l9 FOREIGN PATENTS 168,129 8/1959 Sweden.

M. HENSON WOOD, IR., Primary Examiner.

R. A. SCHACHER, Assistant Examiner.

